Nonionic contrast agents and coagulation.

Abstract

The chemotoxicity of nonionic and ionic contrast media is discussed with reference to chemical structure. Second-generation nonionic contrast media have the lowest chemotoxicity of any agents because of the uniform distribution of hydrophilic groups around the molecule, which mask the hydrophobic iodine atoms. Previous investigations show that second-generation nonionic agents have the same qualitative hematologic effects as other contrast agents. The less marked quantitative hematologic effects of second-generation contrast media compared with conventional agents are consistent with the low toxicity profile of these agents. A study was conducted in which a nonionic and a conventional ionic contrast medium were observed on microscopic slides after small drops of nonanticoagulated blood were added to each. The disordered aggregations of red cells observed were larger in the nonionic agent but easily dispersed with minimal disturbance, suggesting limited clinical significance. A series of coagulation experiments was conducted in which two types of plastic syringes and glass syringes, containing either iohexol or diatrizoate, were contaminated with blood and inspected for blood clots. An ELISA assay for fibrinopeptide A also was performed. Clot formation was uncommon and appeared to be related to syringe material.